Question

A cubical beaker of edge length $10\text{cm}$ is filled with a liquid of surface tension $0.075\text{N/m}$. Force across an imaginary diagonal on the surface of the liquid is

• A. $\frac{3}{\sqrt{2}}\times {10}^{-2}\text{N}$
• B. $\frac{3}{2}\times {10}^{-2}\text{N}$
• C. $\frac{3}{2\sqrt{2}}\times {10}^{-2}\text{N}$
• D. $3\times {10}^{-2}\text{N}$

Answer 1

The correct option is C $\frac{3}{2\sqrt{2}}\times {10}^{-2}\text{N}$


Length of imaginary diagonal on the surface of liquid,
$L=10\sqrt{2}\text{cm}$
Surface tension of liquid $T=0.075\text{N/m}$
$\Rightarrow$Surface tension is defined as force per unit length on the free surface of liquid.
$\therefore$Force due to surface tension on the imaginary diagonal is
$F=T\times L$
$\Rightarrow F=0.075\text{N/m}\times 10\sqrt{2}\times {10}^{-2}\text{m}$
$\therefore F=\frac{3}{2\sqrt{2}}\times {10}^{-2}\text{N}$